TWI519091B - Method and apparatus for combining space-frequency block coding, spatial multiplexing and beamforming in a mimo-ofdm system - Google Patents

Description

Combining space-frequency block coding, spatial multiplexing and beamforming in MIMO-OFDM systems Method and device

The present invention relates to a wireless communication system, and more particularly to a combination of space-frequency block coding (SFBC) and spatial multiplexing (SM) in a Multiple Input Multiple Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) system. And a method and apparatus for beamforming.

OFDM is a data transmission mechanism that divides data into a plurality of small streams, and each stream is transmitted using subcarriers whose bandwidth is smaller than the total effective transmission bandwidth. The effectiveness of OFDM depends on the selection of these mutually orthogonal subcarriers. When each subcarrier carries a portion of the total user data, it does not affect each other.

An OFDM system has advantages over other wireless communication systems. When the user data is divided into streams carried by different carriers, the effective data rate of each subcarrier is much smaller, and therefore, the symbol period is much larger. A large symbol period can tolerate a large delay spread, so it is not severely affected by multiple paths. Thus, OFDM symbols can tolerate delay spread without the need for complex receiver designs, however, typical wireless systems require complex channel equalization mechanisms to resist multipath degradation.

Another advantage of OFDM is that it is generated at the transmitter and receiver. The inter-subcarriers can be implemented using Inverted Fast Fourier Transform (IFFT) and Fast Fourier Transform (FFT) engines. Since IFFT and FFT are already well known techniques, OFDM can be easily implemented without the need for complex receivers.

The MIMO reference wireless transmission and reception mechanism uses more than one antenna for both the transmitter and the receiver. The advantage of a MIMO system is its spatial diversity or spatial multiplexing, and it can improve the signal-to-noise ratio (SNR) and increase the total processing power.

SFBC is a mechanism for transmitting spatially diverse coded symbols on adjacent subcarriers in a continuous time slot, rather than on the same subcarrier. This SFBC avoids the problem of fast time transforms associated with Spatial Time Block Coding (STBC), however, when combining occurs, the channels on the subcarriers must remain stable.

The present invention relates to a method and apparatus for combining SFBC, SM and beamforming in a MIMO-OFDM system, the system comprising a transmitter having a plurality of transmit antennas, and a receiver having a plurality of receive antennas. The transmitter generates at least one data stream and a plurality of spatial streams, and the number of spatial streams generated depends on the number of transmitting antennas and the number of receiving antennas. The transmitter determines a transmission mechanism based on at least one of SFBC, SM, and beamforming, and the transmitter transmits data to the receiver in the data stream according to the selected transmission mechanism.

100‧‧‧ Implementation of a closed loop mode OFDM-MIMO system

110‧‧‧Transporter

115, 215‧‧‧ data stream

126, 226‧‧‧ transmission antenna

128, 231‧‧‧ receiving antenna

130‧‧‧ Receiver

150‧‧‧Feedback

200‧‧‧ Implementing an open loop mode system

CQI‧‧‧ channel status information

CSI‧‧‧ channel quality information

FFT‧‧‧fast Fourier transform

IFFT‧‧‧Inverse Fast Fourier Transform

MIMO-OFDM‧‧‧Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing

SFBC‧‧‧ space-frequency block coding

SM‧‧‧ Space multiplex

S/P‧‧ ‧ sequence to parallel

1 is a block diagram of an OFDM-MIMO system implementing a closed loop mode, which is configured in accordance with the present invention; and FIG. 2 is an OFDM-MIMO system implementing an open loop mode. Block diagram, which is configured in accordance with the present invention.

The preferred embodiments of the present invention will be described with reference to the drawings, wherein like reference numerals refer to the same elements throughout.

Features of the invention may be integrated into an integrated circuit (IC) or on a circuit comprising a plurality of interconnected components.

The present invention provides a combination of a plurality of SFBC, SM, FD, and beam selection, Selected based on the effective data stream and spatial stream and the number of transmit and receive antennas, this combination provides the flexibility to design a MIMO-OFSM system, as well as a solution for any number of transmit and receive antenna configurations. Each combination is exchanged between performance, reliability, and data rate, so combinations can be selected based on certain criteria, such as robustness, data rate, channel status, or the like. The number of data streams is preferably determined according to a modulation and coding mechanism, the number of which is determined by the number of transmission and reception antennas.

The system operates in two modes: closed loop and open loop. The closed loop is used when Channel Status Information (CSI) is available to the transmitter, while the open loop is used when the CSI is not available to the transmitter. A variant can be transmitted to the legacy station where it provides the advantages of diversity.

In closed loop mode, CSI is used to virtually generate independent channels, which are done by precoding at the transmitter end and further antenna processing at the receiver end to decompose and diagonalize the channel matrix. After the feature root of the wireless channel is expanded, transactions between data rate and robustness can be achieved by using SFBC and/or SM. This mechanism allows for a simple receiver implementation that is simpler than a Minimum Mean Square Error (MMSE) receiver. This combination and traditional technology Comparing, with a higher total processing power over a larger range, this technique allows per subcarrier power/bit load and maintains an acceptable robust link through closed loop operation and CSI feedback. Another advantage of the present technology is that it can be easily implemented on any number of transmitters and receivers.

The CSI can be obtained by the receiver's feedback or by channel interaction at the transmitter. The delay demand and feedback data rate are typically not significant for the inheritance frequency non-selective feature root. In addition, a transmission antenna correction mechanism is required. In addition, channel quality information (CQI) is also used to determine a coding rate and a modulation mechanism for each subcarrier of the subcarrier group. Depending on the number of data streams, the combination is selected with a valid space stream.

1 is a block diagram of an OFDM-MIMO system 100 implementing a closed loop mode, which is configured in accordance with the present invention, the system 100 including a transmitter 110 and a receiver 130. The transmitter 110 includes a channel encoder 112, a multiplexer 114, a power load unit 116, a plurality of optional SFBC units 118, a plurality of sequence-to-parallel (S/P) converters 120, and a transmit beamforming. The device 122, the plurality of IFFT units 124, and the plurality of transmission antennas 126. Preferably, the channel encoder 112 encodes data according to a CQI, which is provided by the receiver 130, and the CQI is used to determine a coding rate and a modulation mechanism of each subcarrier or subcarrier group. The stream is multiplexed by the multiplexer 114 into two or more data streams 115.

The transmission power level of each data stream 115 is adjusted by the power load unit 116 based on the feedback 150 provided by the receiver 130, which adjusts the data rate for each eigenbeam. The power level is used to balance the total transmission power of all eigenbeams (or subcarriers).

The non-essential SFBC unit 118 performs SFBC on the data stream 115, and the SFBC is performed on the eigenbeams and subcarriers of each of the transmitted data rates, the eigenbeams and the subcarriers. The wave pair is selected to ensure an independent channel. The OFDM symbol is carried by the K subcarrier. To carry the SFBC, the subcarrier is divided into L pairs of subcarriers (or subcarrier groups), and the bandwidth of the subcarrier group should be smaller than the coherent carrier of the channel. When combining feature beamforming, this limitation is relaxed due to the frequency insensitivity of the eigenbeam.

The subcarrier group pairs used by block coding are considered independently. The following is an example of SFBC in the Alamouti form for OFDM symbols:

Once the non-essential SFBC unit 118 constructs the OFDM symbols for all of the subcarriers The code block is multiplexed by the S/P converter 120 and input to the transmit beamformer 122, the transmit beamformer 122 assigns a eigenbeam to the transmit antenna, and the IFFT unit 124 Convert data in the frequency domain into data in the time domain.

The receiver 130 includes a plurality of receiving antennas 128, a plurality of FFT units 132, a receive beamformer 134, a plurality of unnecessary SFBC decoding units 136, a demultiplexer 138, a channel decoder 144, and a channel estimation. The device 140, a CSI generator 142, and a CQI generator 146.

The FFT unit 132 converts samples received by the antenna 128 in the time domain into a frequency domain, the receive beamformer 134, the non-essential SFBC decoding unit 136, the demultiplexer 138, and the channel estimator 144. Continue processing samples that are converted to the frequency domain.

The channel estimator 140 generates a channel matrix that uses one of the training sequences transmitted by the transmitter and decomposes the channel matrix per subcarrier (or per subcarrier group) into two beamforming unit matrices. U and V (U is transmission and V is reception), and a pair of angular matrix D, It is done by singular value decomposition (SVD) or eigenvalue decomposition. The CSI generator 142 generates CSI 147 from the channel estimation result, and the CQI generator generates a CQI 148 according to the decoding result, and the CSI and the CQI are fed back to the transmitter 110 by the receiver 130.

The channel matrix H between the nT transmission antenna and the nR reception antenna can be expressed as follows: The channel matrix H is decomposed by SVD as follows: H = UDV ^H where U and V are a single matrix, and D is a diagonal matrix, U C ^nRxnR and V C ^nTxnT . Next, in terms of transmitting the symbol vector s, the transmission code is simply expressed as follows: x = Vs The received signal becomes as follows: y = HVs + n where n is the noise of the injected channel, and the receiver uses a matched filter Completion of the decomposition: V ^H H ^H = V ^H VD ^H U ^H = D ^H U ^H After normalizing the channel gain of the eigenbeam, the estimate of the transmitted symbol s becomes: The symbol s does not need to perform continuous interference cancellation or the MMSE form detector can detect. The D ^H D system is a pair of angular matrices which are formed by multiplying the characteristic root of H by a diagonal, and therefore, the normalization factor α = D ^-2 . U is the eigenvector of HH ^H , V is the eigenvector of H ^H H, and D is the diagonal matrix of the singular value of ^H (the square root of the eigenvalue of HH ^H ).

If the non-essential SFBC unit 118 and the non-essential SFBC decoding unit 136 are removed by the transmitter 110 and the receiver 130, respectively, the transmitter 110 and the receiver 130 can be used by the SM.

In open loop mode, the combination of spatial frequency coding and spatial expansion in the transmitter 110 provides diversity without the need for CSI 147. The CQI 148 is used to determine the coding rate and modulation of one subcarrier or subcarrier group. This coding rate and modulation mechanism determine the number of data streams. Depending on the number of streams, the combination can be efficiently streamed.

2 is a block diagram of a system 200 implementing an open loop mode, which is configured in accordance with the present invention, the system 200 including a transmitter 210 and a receiver 230. In this open loop mode, the combination of spatial frequency coding and spatial expansion in the transmitter 210 provides a variety of directions without requiring CSI. This mechanism variant can also be used when operating on legacy IEEE 802.11a/g user devices.

The transmitter 210 includes a channel encoder 212, a multiplexer 214, a power load unit 216, a plurality of SFBC units 218, a plurality of sequence-to-parallel (S/P) converters 220, and a beamformer network ( BFN) 222, a plurality of IFFT units 224, and a plurality of transmission antennas 226. As in the closed loop mode, the channel encoder 212 uses the CQI to determine the coding rate and modulation for each subcarrier or subcarrier group, and the encoded data stream 213 is multiplexed by the multiplexer 214 into two or Multiple data streams 215. The BFN 222 forms N beams in space, where N is the number of antennas 226 that are pseudo-randomly constructed from the BFN matrix operation. The independent subcarrier group for SFBC coding is transmitted in an individual beam.

With the convenience of legacy support, SFBC encoding may not be executed and replaced by more The pattern is achieved by the arrangement of the beams, which improves the diversity and the legacy of legacy IEEE 802.11a/g user equipment.

The receiver 230 includes a plurality of receive antennas 231, FFT units 232, a BFN 234, an SFBC decoding and combining unit 236, and a channel decoder 238. The FFT unit 232 converts the samples received by the receive antenna 231 in the time domain into a frequency domain. The SFBC decoding and combining unit 236 decodes and combines the symbols received by the subcarrier group/feature beam and converts them from parallel to a sequence, which is a conventional technique using cluster size. The symbol uses an MRC combination, and the channel decoder 238 decodes the combined symbol and produces a CQI 240.

If the SFBC unit 218 and the SFBC decoding function of the SBC decoding and combining unit 236 are removed by the transmitter 210 and the receiver 230, respectively, the transmitter 210 and the receiver 230 can be used by the SM.

Examples of SFBC, SM, FD, and beam selection combinations in accordance with the present invention are explained below. S _i represents a group of modulation symbols, the length of the data depends on how many sub-carriers divided into a group sub-carriers into two groups based, each of the S _i comprises a length of half the number of sub-carrier symbol information. d _n represents the singular value of the channel matrix, where d ₁ >d ₂ >d ₃ >...>d _M , and M is the maximum number of singular values (ie, the number of transmission antennas). Rate = 1 indicates the M symbol transmitted and restored per subcarrier during an OFDM symbol. When the transmission and recovery are less than the M symbol, the rate is a small amount. In the FD, S _i is transmitted in one half of the subcarrier, and S _i ^* is transmitted in the other half of the subcarrier.

Single Transmission Antenna Embodiment - Single Input Single Output (SISO) In a SISO embodiment, only one data stream and one spatial stream are implemented. In the case where FD is not used, one symbol is transmitted via one subcarrier. In the case of FD, one symbol is transmitted via two subcarriers, which are summarized in Table 1.

Two transmission antenna embodiments

With two transmit antennas, it can support 2x1 or 2x2 MIMO-OFDM systems and can also support one or two streams.

2x1 MIMO-OFDM closed loop - a data stream embodiment

In a closed loop mode, beam selection with or without FD and SFBC can be used. Since the data transmitted by the beam with smaller singular values will die, the beam selection will pass through the SVD, and the SVD beam with a larger singular value will be selected. In the case of beam selection without FD, a data symbol is transmitted via a subcarrier, and in the case of beam selection with FD, a data symbol can be transmitted via two subcarriers. In the case of beam selection with FD, this rate is one-half of the beam selection without FD, but the reliability will increase.

Although data transmitted on a beam with a smaller singular value will die, two symbols can be transmitted simultaneously through two subcarriers using SFBC. With this mechanism, a data symbol is transmitted by a subcarrier. The performance of this embodiment will be reduced compared to the beam selection example because the second stream with smaller singular values contains only the noise.

An embodiment of a data stream of a 2x1 MIMO-OFDM closed loop is summarized in Table 2.

2x1 MIMO-OFDM open loop - a data stream embodiment

In an open loop mode, SMs with or without FD and SFBC can be used. For SMs without FD (with fixed beamforming matrix), a data symbol is transmitted using the fixed beamforming and subcarriers of each spatial stream of the SM, and in the case of an SM with FD, a data The symbol is transmitted using the fixed beamforming and the two subcarriers of the spatial stream of the SM.

It is possible to combine FD and non-FD. In each embodiment, one symbol is transmitted on two subcarriers of one spatial stream, and one symbol is on one subcarrier of another spatial stream. Send, in the case of SM without FD, the data rate is 3⁄4.

If SFBC with a fixed beamforming matrix is used, the two data symbols of the data stream are transmitted over two subcarriers using two antennas using fixed beamforming, which is half of the SM case without FD.

An embodiment of one of the 2x1 MIMO-OFDM open loop data streams is summarized in Table 3.

Two data stream embodiments of the 2x1 MIMO-OFDM open loop are summarized in Table 4.

2x2 MIMO-OFDM closed loop - a data stream embodiment

In closed loop mode, SM with or without FD, beam selection with or without FD and SFBC may be used. In closed loop mode, two spatial beams can be formed for each subcarrier by SVD.

In the case of an SM without FD, a data symbol is transmitted via one subcarrier per one spatial stream. In the case of an SM with FD, a data symbol is transmitted via two subcarriers using a spatial stream. Combining FD and non-FD is feasible.

In terms of beam selection, select an SVD between two beams per subcarrier The beam, which has a large singular value, is discarded for each other beam of the subcarrier. In terms of beam selection without FD, a data symbol is transmitted over a subcarrier using a spatial stream. In the beam selection with FD, a data symbol is transmitted over two subcarriers using a spatial stream.

Two spatial streams per subcarrier are generated based on the SVD of the channel for each subcarrier, and two data symbols can be transmitted on the two subcarriers using SFBC.

A data stream embodiment of a 2x2 MIMO-OFDM closed loop is summarized in Table 5.

2x2 MIMO-OFDM open loop - a data stream embodiment

In an open loop, SMs with or without FD and SFBC can be supported, the SM is in a fixed beamforming matrix, and two spatial streams per subcarrier can be used.

In the case of an SM without FD, a data symbol is transmitted through each of the space strings. One subcarrier of the stream is transmitted, and in the case of an SM with FD, a data symbol is transmitted via two subcarriers using a spatial stream, and combining FD and non-FD is feasible.

The two data symbols of the data stream are transmitted on the two subcarriers of the spatial stream using the fixed beamforming and SFBC.

The method of transmission is the same as that of the 2x1 system, however, the performance will be better because two receive antennas are used in one receiver.

One of the data stream embodiments of the 2x2 MIMO-OFDM open loop is summarized in Table 6.

2x2 MIMO-OFDM closed loop - two data stream embodiments

In a closed loop mode, an SM with or without FD can be used. The SM system is implemented with SVD beamforming, and two spatial streams are available for each subcarrier. Since there are two data streams, each data stream needs to be assigned a spatial stream, and for the same reason, SFBC cannot be used.

In the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an SM with FD, a data symbol uses a spatial stream via two subcarriers. Sending, combining FD and non-FD is feasible.

The two data stream embodiments of the 2x2 MIMO-OFDM closed loop are summarized in Table 7.

2x2 MIMO-OFDM open loop - two data stream embodiments

In an open loop, the SM is implemented in a fixed beamforming matrix, and two spatial streams are available for each subcarrier, as described above, each spatial stream is assigned a spatial stream.

In the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an SM with FD, a data symbol uses a spatial stream via two subcarriers. Sending, combining FD and non-FD is feasible.

The two data stream embodiments of the 2x2 MIMO-OFDM open loop are summarized in Table 8.

Three transmission antenna embodiments

With three transmit antennas, it can support 3x1, 3x2, and 3x3 MIMO-OFDM systems, and can also support one, two, or three data streams.

3x1 MIMO-OFDM closed loop - a data stream embodiment

In a closed loop mode, beam selection with or without FD and SFBC can be used, the beam system is generated by SVD beamforming, and in terms of beam selection, a spatial beam is selected (only one beam is available, since the other The two beams have only noise and will die. The beam with the largest singular value is chosen.

In the case of beam selection without FD, a data symbol is transmitted via one of the selected spatial streams, and in the case of beam selection with FD, a data symbol is passed through two sub-streams of the selected space. Carrier transmission.

For SFBC with SVD beamforming, two spatial streams are selected for each subcarrier: one corresponding to the largest singular value and the other corresponding to one of the remaining ones, however, even though two data symbols are permeable to both The subcarriers are transmitted simultaneously using SFBC, and the performance is still very low, because a space stream contains only noise.

A data stream embodiment of a 3x1 MIMO-OFDM closed loop is summarized in Table 9.

3x1 MIMO-OFDM open loop - a data stream embodiment

In an open loop embodiment, the SM and SFBC are implemented in a fixed beamforming matrix and three spatial streams are available.

In the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an SM with FD, a data symbol is transmitted via two subcarriers per spatial stream. One. Combining FD and non-FD is feasible. One data stream is transmitted on one spatial stream via one subcarrier and one symbol is transmitted on one of the other two spatial streams via one subcarrier, or one data symbol is in two The spatial stream is transmitted via two subcarriers and one symbol is transmitted over another spatial stream via a subcarrier.

SFBC can be implemented with or without FD. Between each of the three spatial streams of the subcarrier, two spatial streams are used by the SFBC, and the other is used for the independent data symbols. Therefore, at each instant, each subcarrier can be sent three times. Symbols.

One of the data stream embodiments of the 3x1 MIMO-OFDM open loop is summarized in Table 10.

3x1 MIMO-OFDM (Open Loop) - Two Data Streaming Embodiments

In this embodiment, an open loop structure can be used to send and reply two streams of data. The SM and SFBC are implemented in a fixed beamforming matrix, and the two data streams are divided into three spatial streams per subcarrier.

In the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an SM with FD, a data symbol is transmitted via two subcarriers per spatial stream. One. Combining FD and non-FD is feasible.

In the case of SFBC, one data stream is sent and replied using SFBC, while the other data stream does not use SFBC. Between three spatial streams per subcarrier, two spatial streams are used by the SFBC and the other is used for another data stream.

The two data stream systems of the 3x1 MIMO-OFDM open loop are summarized in Table 11.

3x1 MIMO-OFDM (Open Loop) - Three Data Streaming Embodiments

An open loop structure can be used to send and reply three streams of data. The SM and SFBC are implemented in a fixed beamforming matrix, and the three data streams are divided into three spatial streams per subcarrier, and SFBC cannot be used in this embodiment.

In the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an SM with FD, a data symbol is transmitted via two subcarriers per spatial stream, Combining FD and non-FD is feasible.

The three data stream embodiments of the 3x1 MIMO-OFDM open loop are summarized in Table 12.

3x2 MIMO-OFDM closed loop - a data stream embodiment

In this embodiment, two spatial streams are available, two beams are selected between each of the three sub-carriers through the SVD, and two SVD beams with larger singular values are selected.

In the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an SM with FD, a data symbol is transmitted via two subcarriers per spatial stream, Combining FD and non-FD is feasible.

In terms of SFBC, two spatial streams per subcarrier are selected, and two symbols are transmitted at the same time using SFBC through two subcarriers. With this mechanism, two data symbols can be replied via two subcarriers.

One of the data stream embodiments of the 3x2 MIMO-OFDM closed loop is summarized in Table 13.

3x2 MIMO-OFDM open loop - a data stream embodiment

One of the 3x2 open loop data streams is the same as one of the 3x1 open loop data streams.

3x2 MIMO-OFDM closed loop - two data stream embodiments

In this embodiment, two spatial streams are available, two beams are selected from each of the three sub-carriers generated by the SVD, and two SVD beams having larger singular values are selected.

In the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an SM with FD, a data symbol is transmitted via two subcarriers per spatial stream, Combining FD and non-FD is feasible.

The two data stream systems of the 3x2 MIMO-OFDM closed loop are summarized in Table 14.

3x2 MIMO-OFDM Open Loop - Two Data Streaming Embodiments The two data streams of the 3x2 open loop are the same as the two data streams of the 3x1 open loop.

3x2 MIMO- OFDM -Three Data Streaming Embodiments The three data stream embodiments of the 3x2 MIMO-OFDM system are identical to the three data stream embodiments of the 3x1 MIMO-OFDM system.

3x3 MIMO-OFDM closed loop - a data stream embodiment

In a closed loop embodiment, three spatial streams can be used. In the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an SM with FD, a data symbol is transmitted via two subcarriers per spatial stream, Combining FD and non-FD is feasible.

In terms of SFBC, two spatial streams are selected from three spatial streams. Preferably, two bad spatial streams are selected for each subcarrier, which have smaller singular values, two symbols. The SFBC is transmitted simultaneously on two bad spatial streams of two subcarriers, and in the case of another good stream per carrier, a data symbol is not transmitted using SFBC.

In the case of non-SFBC spatial stream, if FD is used, a data symbol is transmitted via one of the spatial streams, and if FD is not used, a data symbol is transmitted via two subcarriers of the spatial stream. .

One of the data stream embodiments of the 3x3 MIMO-OFDM closed loop is summarized in Table 15.

3x3 MIMO-OFDM open loop-a data stream embodiment

In an open loop embodiment, all of the selectivity of one of the 3x1 open loop data stream embodiments can be used.

3x3 MIMO-OFDM closed loop - two data stream embodiments

In this embodiment, three spatial streams are available, and two data streams are divided into three spatial streams per subcarrier. In a closed loop, in the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an SM with FD, a data symbol is streamed through each space. The transmission of the two subcarriers, combined with FD and non-FD is feasible.

In terms of SFBC, two spatial streams are selected from three spatial streams. Preferably, two bad spatial streams per subcarrier are selected, which have smaller singular values. For a data stream, two symbols are transmitted simultaneously on two bad spatial streams of two subcarriers using SFBC, and another data stream is transmitted to another good stream per carrier. Not sent using SFBC.

For non-SFBC spatial streams, if FD is not used, a data symbol is sent via one subcarrier of the spatial stream, and if FD is used, a data symbol is transmitted via this Two subcarriers of the spatial stream are transmitted.

The two data stream embodiments of the 3x3 MIMO-OFDM closed loop are summarized in Table 16.

3x3 MIMO-OFDM open loop - two data stream embodiments

In an open loop embodiment, all of the selectivity of the two data stream embodiments of the 3x1 open loop can be used.

3x3 MIMO-OFDM closed loop - three data stream embodiment

This embodiment has three spatial streams available, and three data streams are divided into three spatial streams per subcarrier. In a closed loop, in the case of an SM without FD, a data symbol is transmitted via one subcarrier per one spatial stream, and in the case of an SM with FD, a data symbol The number is transmitted via two subcarriers per stream, and it is feasible to combine FD and non-FD.

The three data stream embodiments of the 3x3 MIMO-OFDM closed loop are summarized in Table 17.

3x3 MIMO-OFDM open loop-three data stream embodiment

In an open loop embodiment, all of the selectivity of the 3x1 open loop data stream embodiment can be used.

Four transmit antenna embodiments

With four transmit antennas, it can support 4x1, 4x2, 4x3, and 4x4 MIMO-OFDM systems, and can also support one, two, three, or four data streams.

4x1 MIMO-OFDM closed loop - a data stream embodiment

This embodiment has only one spatial stream. In a closed loop embodiment, one of each of the four beams of the subcarrier generated by the SVD is selected, and the selected SVD beam has the largest oddity. Different value.

In the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream. In the case of an SM with FD, a data symbol is transmitted via two subcarriers per spatial stream. Sent.

For SFBC with SVD beamforming, two spatial streams are selected between the four beams generated by the SVD per subcarrier: one corresponding to the maximum singular value and the other corresponding to one of the remaining ones, However, even if two data symbols can be transmitted simultaneously using SFBC through two subcarriers, the performance is still very low, because a spatial stream contains only noise.

One of the data stream embodiments of the 4x1 MIMO-OFDM closed loop is summarized in Table 18.

4x1 MIMO0OFDM open loop - a data stream embodiment

In an open loop embodiment, the SM is implemented in a fixed beamforming matrix and four spatial streams are available.

In the case of an SM without FD, a data symbol is streamed through each space. One subcarrier is transmitted, and in the case of an SM with FD, a data symbol is transmitted by two subcarriers per spatial stream. Combination FD and non-FD are possible, as shown in Table 19. For a data stream, these combinations may not be used to maintain the same quality of all data symbols.

The combination of SM and SFBC with a fixed beamforming matrix is feasible. The first option is a 2x2 SFBC and two SMs. For a data stream, this selection is not used to maintain the same quality of all data symbols, and the other two spatial streams for that subcarrier are used by the SM of the other two data symbols of the data stream. In the absence of FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an FD, a data symbol is transmitted via two subcarriers per spatial stream. It is possible to combine FD and non-FD, as shown in Table 20.

The second option is to use two 2x2 SFBCs. The four spatial streams per subcarrier are divided into two groups, one for each two streams, and each group is assigned to each SFBC. For each instant, four (4) data symbols are transmitted on the two subcarriers using the fixed beamforming and two 2x2 SFBCs.

4x1 MIMO-OFDM (Open Loop) - Two Data Streaming Embodiments

In this embodiment, the open loop should be used to send and reply two streams of data. The SM system is implemented with the fixed beamforming matrix, and the 4E14 two data streams are divided into four spatial streams per subcarrier.

In the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an SM with FD, a data symbol is transmitted via two subcarriers per spatial stream. One. Combining FD and non-FD is possible, as shown in Table 21, and the combination of Cases 1 and 3 in Table 21 is not used to maintain the same quality for each data symbol of the data stream of 6301.

The combination of SM and SFBC with a fixed beamforming matrix is feasible. The first option is a 2x2 SFBC and two SMs. One data stream is assigned to the SFBC, and the other data stream is sent by the SM. The two spatial streams of the subcarrier are used by the SFBC, and the other two spatial streams of the subcarrier are given. SM is used. In the absence of FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of FD, a data symbol The number is transmitted via two subcarriers per stream. It is possible to combine FD and non-FD, as shown in Table 22, this combination is not used to maintain the same quality of each data symbol of the data stream, which uses SM.

The second option is to use two 2x2 SFBCs, each of which is assigned to two separate 2x2 SFBCs. The four spatial streams per subcarrier are divided into two groups, one for each two streams, and each group is assigned to each SFBC. For each instant, two (2) data symbols are transmitted using the fixed beamforming and on each of the 2x2 SFBCs on two subcarriers.

4x1 MIMO-OFDM (Open Loop) - Three Data Streaming Embodiment

In this embodiment, an open loop structure can be used to send and reply three streams of data. The SM system is implemented with a fixed beamforming matrix, and three data streams are divided into four data symbols per subcarrier, and all combinations in Table 21 can be used.

The combination of SM and SFBC with a fixed beamforming matrix is feasible. The first option is a 2x2 SFBC and two SMs. Two spatial streams per subcarrier use SFBC, one data stream is transmitted using SFBC and the fixed beamforming, and the other two spatial stream families of the subcarrier use the other two data streams. . In the absence of FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an FD, a data symbol is transmitted via two subcarriers per spatial stream. It is possible to combine FD and non-FD, as shown in Table 23.

The SFBC 4x1 MIMO-OFDM Open Loop Data Streaming Embodiment is summarized in Table 23.

4x1 MIMO-OFDM (Open Loop) - Four Data Streaming Embodiment

In this embodiment, an open loop structure can be used to send and reply four data streams. The SM system is implemented with a fixed beamforming matrix, and four data streams are divided into four spatial streams per subcarrier, and all methods in Table 21 can be used.

4x2 MIMO-OFDM closed loop - a data stream embodiment

In this embodiment, two spatial streams are available, two beams are selected between each of the four sub-carriers through the SVD, and two SVD beams with larger singular values are selected. In the case of an SM without FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of an SM with FD, a data symbol is transmitted via two subcarriers per spatial stream, It is possible to combine FD and non-FD as shown in Table 24.

In terms of SFBC, two spatial streams per subcarrier are selected, which have larger singular values. Two symbols are transmitted at the same time using SFBC through two subcarriers. With this mechanism, two data symbols can be replied via two subcarriers.

One of the data stream embodiments of the 4x2 MIMO-OFDM closed loop is summarized in Table 24.

4x2 MIMO-OFDM open loop - a data stream embodiment

In this embodiment, all of the selections of one of the 4x1 open loop data stream embodiments can be used.

4x2 MIMO-OFDM closed loop - two data stream embodiments

In this embodiment, two spatial streams are available, two beams are selected from each of the four sub-carriers generated by the SVD, and two SVD beams having larger singular values are selected. In the case of no FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of FD, a data symbol is transmitted via two subcarriers per spatial stream, combined with FD And non-FD are feasible.

The two data streams of the 4x2 MIMO-OFDM closed loop are summarized in Table 25.

4x2 MIMO-OFDM open loop - two data stream embodiments

In this embodiment, all of the options for the two data stream embodiments of the 4x1 open loop can be used.

4x2 MIMO-OFDM open loop-three data stream embodiment

In this embodiment, all of the selections of the 4x1 open loop data stream embodiment can be used.

4x2 MIMO-OFDM open loop-four data stream embodiment

In this embodiment, all of the four data stream embodiments of the 4x1 open loop can be used.

4x3 MIMO-OFDM open loop-a data stream embodiment

In this embodiment, the SM is implemented in SVD beamforming, and three spatial streams are available, and three spatial streams with larger singular values are selected. In the case of no FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of FD, a data symbol is transmitted via two subcarriers per spatial stream, combining FD and non FD is feasible, as shown in Table 26.

In terms of SFBC, three spatial streams per subcarrier are selected, which have larger singular values. In the meantime, two spatial streams, preferably two bad spatial streams, are assigned to the SFBC. Two symbols are transmitted simultaneously on the two bad spatial flows of the two subcarriers using SFBC, and in terms of the optimal spatial stream per carrier, a data symbol is not sent using SFBC. give away. For the latter, in the absence of FD, a data symbol is transmitted via one subcarrier per spatial stream, whereas in the case of FD, a data symbol is transmitted via two subcarriers per spatial stream.

One of the data stream systems of the 4x3 MIMO-OFDM closed loop is summarized in Table 26.

4x3 MIMO-OFDM open loop - two data stream embodiments

In this embodiment, all of the 4x1 data stream selections are available.

4x3 MIMO-OFDM closed loop - two data stream embodiments

In this embodiment, the SM system is implemented by SVD beamforming, and three spatial streams are available. The two data streams are divided into three spatial streams for each subcarrier, and all the methods in Table 26 are It can be used in this embodiment.

In terms of SFBC, a data stream is transmitted using SFBC, and three spatial streams per subcarrier are selected, which have larger singular values. In between, two space strings The stream, preferably two bad spatial streams, is assigned to the SFBC. Two symbols are transmitted simultaneously on the two bad spatial flows of the two subcarriers using SFBC.

Another data is sent using SM, and all of the SFBC methods in Table 26 can be used in this embodiment.

The two data stream embodiments of the 4x3 MIMO-OFDM closed loop are summarized in Table 27.

4x3 MIMO-OFDM open loop - two data stream embodiments

In this embodiment, all of the options of the 4x1 data stream embodiment can be used.

4x3 MIMO-OFDM closed loop - three data stream embodiment

In this embodiment, the SM system is implemented with SVD beamforming, and three spatial streams are available, and three data streams are divided into three spatial streams per subcarrier. In the absence of FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of FD, a data symbol The number is transmitted via two subcarriers per spatial stream, and combining FD and non-FD is feasible.

The three data stream embodiment of the 4x3 MIMO-OFDM closed loop is summarized in Table 28.

4x3 MIMO-OFDM open loop-three data stream embodiment

In this embodiment, all of the selections of the 4x1 third data stream embodiment can be used.

4x3 MIMO-OFDM closed loop-four data stream embodiment

In this embodiment, all of the selections of the 4x1 fourth data stream embodiment can be used.

4x4 MIMO-OFDM closed loop - a data stream embodiment

In this embodiment, the SM is implemented by SVD beamforming, and four spatial streams are available. In the case of no FD, a data symbol is transmitted via one subcarrier per one of the spatial streams. In the case of FD, a data symbol is transmitted via two subcarriers per spatial stream, and FD and non-FD are combined, as shown in Table 29.

The first option is to use a 2x2 SFBC and two SMs. By each singular value of the subcarrier, two spatial streams, preferably two bad spatial streams, are selected, which have smaller singular values. The data symbol is transmitted on the two bad spatial streams using SFBC, and the two data symbols are transmitted on the other two good spatial streams per subcarrier using SM instead of SFBC. In the case of no FD, a data symbol is transmitted via one subcarrier per spatial stream, and in the case of FD, a data symbol is transmitted via two subcarriers per spatial stream, combining FD and non FD is feasible, as shown in Table 30.

The second option is to use two 2x2 SFBCs, each of which is assigned to a separate 2x2 SFBC. Each of the four spatial streams of the subcarrier is divided into two groups, each group having two spatial streams, and each group is assigned to each SFBC. In each instant aspect, the four (4) data symbols of the data stream on the two subcarriers are transmitted using SVD beamforming and two 2x2 SFBC.

One of the data stream embodiments of the 4x4 MIMO closed loop of SM is summarized in Table 29, and one of the data stream embodiments of the 4x4 MIMO closed loop of SFBC is summarized in Table 30.

4x4 MIMO-OFDM open loop - a data stream embodiment

In this embodiment, all of the 4x1 data stream embodiments can be used.

4x4 MIMO-OFDM closed loop - two data stream embodiments

In this embodiment, the SM is implemented in SVD beamforming and there are four spatial streams available. The two data streams are divided into four spatial streams per subcarrier. All of the methods in Tables 29 and 30 can be used.

4x4 MIMO-OFDM open loop - two data stream embodiments

In this embodiment, all of the options of the 4x1 data stream embodiment can be used.

4x4 MIMO-OFDM closed loop - three data stream embodiment

In this embodiment, the SM is implemented in SVD beamforming and there are four spatial streams available. The three data streams are divided into four spatial streams per subcarrier. All methods of Table 29 can be used.

In terms of SFBC, one 2x2 SFBC and two SMs are used for three data streams, and one data stream is transmitted using the 2x2 SFBC and SVD beamforming. By each singular value of the subcarrier, two spatial streams, preferably two bad spatial streams, are selected, which have smaller singular values. Two data symbols of one data stream on two subcarriers are transmitted on two bad spatial streams per subcarrier using SFBC and beamforming, and SM and SVD beams are used in the other two data streams. Formed to send. The two data symbols are transmitted via subcarriers using two other good spatial streams per subcarrier, which are sent to the other two data streams using SM instead of SFBC. In this embodiment, in the case of no FD, a data symbol is transmitted via one subcarrier per one spatial stream, and in the case of FD, a data symbol is transmitted via two subcarriers per spatial stream. It is feasible to combine FD and non-FD, as shown in Table 31.

The three data stream embodiments of the 4x4 MIMO-OFDM closed loop of SFBC are summarized in Table 31.

4x4 MIMO-OFDM open loop-three data stream embodiment

In this embodiment, all selections of the 4x1 third data stream can be used.

4x4 MIMO-OFDM closed loop - four data stream embodiment

In this embodiment, the SM is implemented in SVD beamforming and there are four spatial streams available. The four data streams are divided into four spatial streams per subcarrier. All methods of Table 29 can be used.

4x4 MIMO-OFDM open loop-four data stream embodiment

In this embodiment, all selections of the 4x1 fourth data stream can be used.

Although the features and elements of the present invention are described in a particular combination of the embodiments, each feature or element of the embodiments can be used alone, without being combined with other features or elements of the preferred embodiment, or with / No combination of other features and elements of the invention. While the invention has been described in terms of the preferred embodiments, it will be apparent to those skilled in the art The above description is intended to be illustrative, and does not limit the invention in any way.

100‧‧‧ Implementation of a closed loop mode OFDM-MIMO system

110‧‧‧Transporter

115‧‧‧ data stream

126‧‧‧ transmit antenna

128‧‧‧ receiving antenna

130‧‧‧ Receiver

150‧‧‧Feedback

CQI‧‧‧ channel status information

CSI‧‧‧ channel quality information

FFT‧‧‧fast Fourier transform

IFFT‧‧‧Inverse Fast Fourier Transform

MIMO-OFDM‧‧‧Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing

SFBC‧‧‧ space-frequency block coding

S/P‧‧ ‧ sequence to parallel

Claims (3)

A transmission device comprising: a circuit configured to transmit a first data symbol using a first set of orthogonal frequency division multiplexing (OFDM) subcarriers using spatial frequency block coding (SFBC); Each pair of first data symbols is SFBC encoded to be transmitted on two of the four antennas and not transmitted on the other two of the four antennas; and the circuit is further configured to The receiving device receives channel state information (CSI); wherein the CSI includes a channel quality information (CQI) for each group of sub-carriers of the complex array for each of the sub-carriers of the complex array; wherein the circuit is further Configuring to determine, for each set of subcarriers of the complex array, a number of streams transmitted using multiple input multiple output (MIMO) spatial multiplexing and a tone for each group of subcarriers for the complex array Transforming and encoding to return the CQI of the group; wherein at least two of the complex arrays have a different number of streams and different modulation and coding schemes; wherein the circuitry is configured to transmit using MIMO spatial multiplexing The complex array Two data symbols, the plurality of groups having the number of streams determined respectively. A method for use by a transmission device, the method comprising: transmitting, by using the spatial frequency block coding (SFBC), a first set of orthogonal frequency division multiplexing (OFDM) subcarriers by the transmission device a data symbol; wherein each pair of the first data symbols is SFBC encoded to be transmitted on two of the four antennas, and not transmitted on the other two of the four antennas; The transmitting device receives channel state information (CSI) from a receiving device; wherein the CSI includes a channel quality information (CQI) for each of the subcarriers of the complex array for each of the complex array of subcarriers; Determining, for each set of subcarriers of the complex array, a number of streams transmitted using multiple input multiple output (MIMO) spatial multiplexing and a modulation of each group of subcarriers for the complex array Encoding to return the CQI of the group; where the complex At least two of the arrays have a different number of streams and different modulation and coding schemes; and MIMO spatial multiplexing is used by the transmission device to transmit a second data symbol using the complex array, the complex array having a string The number of streams is determined by the flow. A receiving device comprising: a circuit configured to receive at least one of a first data symbol and a second data symbol from a transmitting device and to recover data from the at least one first data symbol and the second data symbol Where the first data symbols are transmitted using a first set of orthogonal frequency division multiplexing (OFDM) subcarriers, the first set of orthogonal frequency division multiplexing (OFDM) subcarriers using spatial frequency blocks Encoding; wherein each pair of the first data symbols is SFBC encoded to be transmitted on two of the four antennas, not transmitted on the other two of the four antennas; and the circuit is configured Transmitting channel state information (CSI) to the transmitting device; wherein the CSI includes a channel quality information (CQI) for each of the subcarriers of the complex array for each of the plurality of subcarriers of the complex array; The circuit is further configured to determine, for each set of subcarriers of the complex array, a number of streams transmitted using multiple input multiple output (MIMO) spatial multiplexing and each of the subcarriers for the complex array Group modulation and coding Wherein at least two of the plurality of complex arrays have a different number of streams and different modulation and coding schemes; and wherein the second data symbols are transmitted using the determined number of the complex arrays having the stream These streams use multiple input multiple output (MIMO) spatial multiplexing.